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Drone comb loaded with mites

I checked my back yard top bar hive which was started with a feral swarm. It seems to be doing well, though it has stopped expanding after filling about two thirds of its four foot length. I have harvested about a bar of honey over each of the last two months, and added a bar to the brood nest 4 times. Yesterday I pulled a heavy bar of capped honey--the bottom third was drone comb. I was a little surprised to find 2-4 mites on each of the drone larvae.

I haven't done an alcohol wash. Does the count in drone brood correlate with a dangerous level of varroa indicating need for treatment? How effective is drone comb culling in controlling mites?

Re: Drone comb loaded with mites

I think it is high. Worker cells will be lower rate of infestation than the drone cells, but in my climate with cool spring I think that load of mites would really slow down buildup. Here is a pic of some drone comb I culled in August. Did not find any visible mites. The culling was mostly to check the effectiveness of the OA vaporization I did in April.

Re: Drone comb loaded with mites

What I would do if I found that many mites on the drone brood as you did, is take your capping scratcher and go throught the hive and scratch open all the drone brood so the bees will remove them and the mites.

Re: Drone comb loaded with mites

If 25% of drone larvae have a mite in them, at that level it is likely that 6% of worker brood will have mites in them.

But you have to sample around 100 drone cells because the mites can "cluster" in one small area of comb and give a wrong reading in a small sample.

The 25% drone brood infestation is considered a critical level for the hive, the level at which many textbooks recommend the hive is treated. For you though, it is a simple matter to remove the drone brood thereby removing a good portion of the mites. As above, the comb can be discarded, or frozen then returned to the hive.

Just to complicate things , there is a body of thought in the treatment free community, that mite levels should be left to run their course in the hope that maybe the hive will throw off the mites. However if this is your only hive & you want to play safe you would treat it or at the very least remove drone brood and continue to monitor.

Re: Drone comb loaded with mites

You will need to completely remove the drone brood. If you just scratch them open and leave them in the hive the mites will crawl out of the opened cells and into another one faster than the bees can remove them.
Dave

Re: Drone comb loaded with mites

I have frozen complete deep frames of drone and returned it to the hive. It was a bad experience since the bees seem to dump most of the carcasses within a few feet of the entrance. That amounts to 4 or 5 pounds of stinking mess that attracts flies, ants, hornets etc. Even covering it with ashes the smell lingered for a long while.

You can uncap and blow the larvae out with air hose or a water hose sharp spray nozzle but that is a bit of a mess too, including your glasses. I tried a few foundationless frames and they get drawn out quickly and you can just cut the whole slab out leaving a fringe on the top bar and throw it back in immediately. My chickens enjoy cleaning the comb for me!

Re: Drone comb loaded with mites

My fish pond took care of the drone larvae--no chickens. Are bees the gateway drug for chickens or vise versa?

The section I removed was the only drone comb I saw and there had to be at least 300 mites in that section of about 150 cells with an estimated 90% infestation rate. Guess that means treatment, but I'll try my first alcohol wash tomorrow to confirm.

Re: Drone comb loaded with mites

The mites prefer drones, and a new natural method of control is to introduce foundation sized for drones, and then remove and destroy it, therby lowering the colony mite population. Try it on purpose, you seem to have the perfect hive to experiment with. Good luck!

Re: Drone comb loaded with mites

Jfb58, if you do go the treatment route, might I recommend Apivar (not Api-Life-Var, a different product). This is because there are many pitfalls treating hives especially in a TBH. Some treatments such as thymol based ones or organic acid ones are virtually impossible to do effectively in a TBH.
Apivar is pretty fullproof, you just hang the strips between the combs, 2 or 3 strips would do for an average TBH, and you leave them there 8 to 10 weeks. Over that time they leach a chemical that kills the mites. Doesn't get the ones in brood cells so an 8 week time period is to catch 2 drone brood cycles just incase some mites didn't get caught first time around.
The active ingredient is called Amitraz, it is an artificial chemical, however it has a very short 1/2 life, ie, once it is out of the strip and among the bees it is chemically unstable and breaks down in a few days so does not remain in the hive for years like some other chemicals do.
With your high mite count, the hive may already be in more trouble than you realise, with possibly all the worker brood affected as well, and sometimes it can be too late to save such a hive even if all mites are removed because they cannot get a cycle of healthy brood through. So if you do decide to treat, do it soon as.

Re: Drone comb loaded with mites

>Then the remaining mites....those that prefer worker brood.....would have a much lower reproductive success rate and the mite loads would grow much more slowly.
I like it.

But Apis cerana has the opposite arrangement and survive Varroa quite well. The Varroa only prefer the drones and the workers are not damaged. I think you already have the problem that they don't perfer the drones enough and that's why your workers are damaged. Less mites does not necessarily mean less damage as the cerana have shown us.

Re: Drone comb loaded with mites

I did a count, had 7 mites on 203 nurse bees, 3.5%. These are locally adapted survivors from a swarm trap collected 6 months ago: not too bad to work with, but they were plenty p-o'ed when I brushed off a brood comb. This isn't my only hive, and no monetary risk, seems like a good opportunity to watch and see what happens. Mr. Bush, I look forward to meeting you in Arizona next month, hope you are still coming!

Re: Drone comb loaded with mites

That does seem to be the common view, but in this study they said they COULD reproduce contrary to what had been thought. Of 720 worker cells, 3 cells were infested with Varroa. of 132 drone cells 18 were infested. That is a ratio on workers of 0.0041666666666667 and a ration on drones of 0.1363636363636364 or a 32 times preference for drones... I would say they prefer drones and it looks like that is the reason they can tolerate them.

Re: Drone comb loaded with mites

Originally Posted by Michael Bush

this study they said they COULD reproduce contrary to what had been thought. Of 720 worker cells, 3 cells were infested with Varroa.

Three worker cells containing a foundress mite hardly indicates that they can successfully reproduce in them.
You implied in an earlier post that culling drone cells would put selection pressure on those who reproduced in worker cells. The purpose of my initial response was to point out the silliness of such a 'hypothesis'. Getting bogged down in an equally ridiculous debate is a waste of both my time and yours.

Let me never fall into the vulgar mistake of dreaming that I am persecuted whenever I am contradicted. - Emerson